The present invention is related to digital photography, to digital photography cameras and to an imaging device for same.
One of the most important technologies in digital photography is the implementation of two dimensional imaging devices such as CCDs (Charge Couple Device) or CMOS (Complementary Metal Oxide Semiconductor) sensors in digital photography in general and in the body of standard camera format in particular.
In the case of a standard camera body, it is desired that the imaging device will function as a complete substitute for photographic film. This should provide an imaging area of the same size as the film exposed area and a geometry that enables the placement of the imaging device sensitive area at the film focal plane.
The imaging device is thick relative to standard photography film and is larger in size than its imaging area. These geometrical restrictions generate conflicts with standard camera bodies and therefore the imaging device is unsuitable as a complete substitute for a film.
Present art of digital cameras provide three methods for the implementation of an imaging device in a body of standard format.
The first solution involves building a camera body especially designed for accommodating an imaging device in the image plane. This solution is not suitable for use with the large selection of commercially available camera bodies. It is limited to camera bodies especially designed and manufactured for the specific imaging device. Such a solution is provided in StudioCam, manufactured by Agfa-Gevaert of Germany.
In a second solution, an imaging device is supplied which is smaller than the standard film format and is implemented in camera bodies which do not have a focal-plane shutter. This solution enables the implementation of the imaging device in commercially available camera bodies but many such cameras with a focal plane shutter may introduce serious mechanical difficulties. Furthermore, it is inconvenient for the photographer owing to the smaller imaging format. An example of a camera based on this solution is the CatchLight, manufactured by Leaf Systems, Inc. of Bedford, Mass., USA.
In the third method, an optical relay is used to transfer the image from the focal plane of the camera to the focal plane of the imaging device. Usually, magnification is used to provide an effective format which is the same as the film format. Such a solution is provided in the Fujix DS-505/DS-515, manufactured by Fuji Photo Film Co. of Japan. The drawbacks of this solution are costly optical relay, added weight of the optical relay and reduction of optical performance (sharpness and vignetting).
Imaging devices which are intended for use in the visible domain, such as the imaging devices of the present invention, have to be invariably protected by a glass cover. The glass cover also acts as a spectral filter, which is impregnated or coated with material that cuts off the infrared radiation. In the present art, this glass plate is mounted at a small distance from the imaging device itself and thus separated from the imaging device by an air gap. This configuration requires an anti-reflective coating on the glass plate in order to prevent the creation of imaging ghosts caused by internal reflections of rays in the glass, prior to completion of the optical path to the plane of the imaging device, due to the difference in the refraction index of air and the glass plate.
This present art configuration has several disadvantages. The anti-reflective coating and the infrared coating, if it exists, are potential causes of quality problems. For example, the coatings may easily be damaged by cleaning, which is required whenever the camera back containing the imaging device is removed. Additionally, the coating may peel during the handling required for camera back assembly. Furthermore, the cost of infrared cutoff coating or of infrared cutoff glass is relatively high and only special cleaning materials may be used to clean the coated glass.
The present invention provides improved imaging devices and cameras including the imaging devices for imaging, such as in digital photography.
According to one embodiment of the present invention the imaging device includes an imaging die having an electrical circuit on a surface thereof, a glass cover having a first surface and a second surface, and connecting means for connecting the first surface of the glass cover to the surface of the imaging die, wherein the connecting means have a refractive index substantially equal to the refractive index of the glass cover.
According to another embodiment of the present invention there is provided a camera including: a camera body, and an imaging device including: an imaging die having an electrical circuit on a surface thereof, a glass cover having a first surface and a second surface, and connecting means for connecting the first surface of the glass cover to the surface of the imaging die, wherein the connecting means have a refractive index substantially equal to the refractive index of the glass cover.
According to yet another embodiment of the present invention the connecting means is glue.
According to an additional embodiment of the present invention the connecting means includes spectral filtering means.
According to yet an additional embodiment of the present invention the first surface of the glass cover is coated with spectral filtering means.
According to a further embodiment of the present invention the spectral filtering means includes an infra-red absorbing filter.